HELLS GRAHAM ISLAND 35 B

This is a short distance south of the half-way camp, and thence the trail
descends in four miles to camp Wilson, the height of which above sea-level,
by aneroid, is 180 feet. On the ridge, midway, hard, felsitie and diabase
rocks of the older series outcrop along the trail, and were seen, also, on some
of the small streams which cross to the north between the half-way camp and
the coal outcrops. Parts of this trail also are difficult to traverse.

Good exposures of shale and sandstone with, occasionally, conglomerate
are seen on a number of these small brooks that rise to the southwest of the
Rokertson trail. In places, these are cut by dykes and masses of volcanic
rock and are, aS a consequence, much disturbed, but where these sources of
disturbance are absent the coal-formation rocks lie nearly flat or dip at
angles of five to fifteen degrees.

The third outcrop, marked on the plan as camp Anthracite, is on a small
brook half a mile southeast of Falls brook by trail. Beds of the ordinary
grey shale and sandstone are seen at the crossing, and on the stream, about
250 yards above the trail, there are other exposures of similar rock in which
the coal seam is located. Work was done on this outcrop some years ago,
principally by a tunnel driven into the east bank to a distance of about
forty feet. The shale and coal, where opened up, were much broken, the latter,
generally—from the samples seen—of impure quality, and the economic
value of the deposit is small. The strike of the rocks at the outcrop is
about N. 80° W., the dip east, at a high angle, but as the opening is on
the east side of a steep gully it is probable that the surface rocks are
somewhat displaced by the overlying mass of the hill. The overhanging wall
appears to be a rotten shaly sandstone.

The rocks along this stream, which we have named Anthracite brook,
were examined for some distance above this outcrop. At about 100
yards the shale and sandstone change the strike to N. 60° W., with
an east dip. Several small partings or streaks of coaly matter were ob-
served; the rocks are nearly vertical and the shale is much crushed. A
few yards farther up, large ledges of bluish-grey sandstone, similar to the
rock on Falls brook, are exposed in a small fall of 15 to 20 feet and dip
S. 10° E. < 5°-7°. It is probable that the coal of the mine on this
brook is not far from the underlying igneous rock and, as in the case of
the Cowgitz mine, has been crushed by pressure and altered by heat in-
duced by rock movements.

Going southwest on this brook towards Mount Etheline similar flat lying
sandstone and shale are exposed for several hundred yards. Crossing in
the same direction to the upper part of Falls brook they are again seen in
broad flat ledges. The elevation of this outcrop is 1,000 feet, or
150 feet above Camp Robertson. From the upper part of this